The invention relates to a clamping joint (fitting) for pipes or hoses of polymer material or of a compound material with a base pipe of polymer material.
A clamping connector according to the general category and with a support sleeve is known from DE 195 14 210 C2 (IVT), the sleeve having several encircling ribs and being bounded at one end thereof by a collar with an annular surface oriented towards the plug-on end, wherein the annular surface lies in a plane perpendicular to the cylinder axis, whilst a pipe end or hose end with a widened cross-section can be plugged onto the other end (plug-on end) of the support sleeve. A displaceable clamping sleeve pushed onto the pipe end or hose end is pressed over the plugged-on pipe end or hose end in order to produce the connection.
The starting point in the case of this clamping connector was that the pipe end clamped in place between the support sleeve and the clamping sleeve does not, as far as possible, find any empty space into which it can deflect. It is thereby ensured that the pressing of the pipe against the ribs or the edges of the ribs is always greater than the internal pressure of the throughflowing medium.
In reality, however, tolerances have to be taken into consideration in the design of the components support sleeve, clamping sleeve and widened pipe end. The xe2x80x9csmallestxe2x80x9d support sleeve, xe2x80x9clargestxe2x80x9d clamping sleeve and xe2x80x9cthinnestxe2x80x9d pipe are to be taken into account. The support sleeve and clamping sleeve are rigid. The pipe end of polymer material or polymer/metal compound material is, in fact, incompressible, but deformable. When the clamping sleeve is pressed on, a part of the excess pipe bulk is forced into the pipe in front of the support sleeve, but the greatest part is piled up in front of the collar. The following disadvantages can result from the piled-up pipe end bulk in front of the collar:
The clamping sleeve cannot be pressed on until abutting the collar, as excess pipe end bulk blocks the way. The intended clamping length between support sleeve and clamping sleeve is thereby not achieved.
The stroke of the pressing tool by which the clamping sleeve is pressed over the pipe is designed so that the clamping sleeve comes into contact with the collar. However, if excess pipe end bulk blocks the way, then a very substantial increase in force through the tool occurs, whereby deformation and/or material damage of the clamping sleeve and/or the collar can happen.
Proposals for the removal of excess pipe end bulk have been made in DE 38 36 124 C2 (Rehau) and DE 295 13 105 U1 (Rehau). The proposals are an annular abutment or web-shaped abutments for the plugged-on pipe end, the height of which in both cases is, however, smaller than the wall thickness of the pipe end. In the case of crosslinked polyethylene (PE-X), which is a particularly suitable material for clamping sleeve connectors, the pipe end widened in socket shape without heating shrinks in an appropriate time onto the support sleeve. When the clamping sleeve is subsequently pressed on, there is then an annular bulging of the excess pipe end bulk over the abutments.
The pressing-on process functions reliably only when the widened pipe end is shrunk onto the support sleeve. In the absence of waiting for complete shrinking on, play is still present between the socket and the support sleeve and the pipe end can be pushed over the abutments by the process of pressing on the clamping sleeve. The pressing on of the clamping sleeve until it abuts the collar is then hardly possible any longer.
The development is directed to the use of compound pipes consisting inter alia of a base pipe of PE-X and an intimately applied sheathing by a metal foil, for example of aluminium. The advantages of compound pipes are: temperature-induced change in length is small, the pipe is stable with respect to sagging between two pipe clamps and a bending of, for example, a permanent 90xc2x0 deflection is possible. A disadvantage, however, is that a shrinking of the widened pipe end no longer takes place. The known abutments at the support sleeve are not sufficient for pipes of that kind and the pipe end can flow over the abutments. The disadvantages resulting therefrom were described in the foregoing. If the socket of a pipe of compound materials is pressed against the abutments according to DE 38 36 124 or DE 295 13 105, a part of the socket then usually bulges in annular manner over the abutments. This can lead to separation of the layers of the pipe material.
The invention therefore has the object, with respect to a clamping connector according to the general category, of removing, in controlled manner, the excess pipe end bulk occurring in front of the collar.
According to the invention this object is met through design of the clamping connector in accordance with the characterising part of claim 1.
Developments and refinements of the invention are claimed in the subclaims.